The present invention relates to a method for co-extruding an elongated food product comprising the following steps of: a) providing a food dough; b) providing a viscous gelling agent comprising collagen; c) co-extruding a strand of food dough and an external layer of viscous gelling agent, wherein the viscous gelling agent at least partially encloses the strand of food dough; and d) performing at least one subsequent processing step.
Such a method of co-extrusion in food products is generally known and described in, among others, Dutch patent NL 6909339. This document describes the coating of a strand of food dough with a coating layer of collagen by means of co-extrusion. Following extrusion the coated strand is guided for strengthening purposes through a coagulation bath. Under the influence of the coagulation solution the collagen coagulates and/or precipitates and the coating layer is strengthened. A strand of food dough is thus formed which is at least partially coated with a strong coating layer of collagen, i.e. casing.
A drawback of the known methods is that the characteristics of the casing material, and therefore the processability of the food product, may change during the manufacturing of the co-extruded elongated food product, i.e. sausage. The change in the characteristics of the casing material is difficult to predict. Even further, the change in the characteristics of the casing material is irreversible. Therefore, once the characteristics of the casing material have been changed the co-extruded elongated food product can no longer be processed to obtain a food product having an acceptable quality.
A particular drawback of the known methods is the use of collagen or collagen comprising viscous gelling agent as a casing material for the co-extrusion of elongated food products are the uncontrolled properties (especially the surface conditions) of the final food products. It has been observed that by changing the process settings after co-extrusion of the strand of food dough ant the casing material, the characteristics of the collagen casing material may irreversibly change. The change may include the change of surface characteristics of the casing material with regard to smoothness of the surface of the food product, i.e. the “look-and-feel” of the food product. By changing the process settings after co-extrusion in subsequent processing step, such as brining, separating, crimping, smoking, drying, packaging, cooking and/or chilling of the co-extruded elongated food product, the obtained food product may, different from the normally desired smooth, nice looking and stable surface, uncontrolled change into a food product with undesired surface conditions like e.g. sticky, inconsistent and/or smudgy surfaces. Such uncontrolled irreversible change in surface characteristics results in the less processability of the food product and, as a consequence, the food product may even have to be discarded.
In view of the above there is a need to enhance the control of the production of co-extruded elongated food products, and more specific to enhance the control of the product characteristics of the casing material during the manufacturing and the further life stages of the food products.